A variety of telecommunications switching systems have been used to establish communication between customer premises equipment (CPE) units and a central office. Most such systems are formed in a "tree" structure, in which the central office is connected to several switching units, which are each connected to several smaller switching units, and so on. At the lowest level of switching units, each unit is connected to one or more CPE units.
To route addressed data or otherwise communicate with one of the CPE units, the central office determines which "branch" services the CPE unit in question. The data is then passed to the switching system for that branch, which in turn passes the data on to the next lower level in the switching hierarchy, and so on, until the data reaches the CPE unit.
This routing scheme requires that each switching system at each level in the hierarchy must store address and routing information for all of the CPE units serviced by it. If the customer base is expanded to include additional CPE units, then all switching systems routing traffic to the new CPE units must be reprogrammed to store the new address and routing information.